The invention relates to a motor vehicle having a central locking system and an anti-theft alarm system and, more particularly, to a motor vehicle having at least two doors and a closable and lockable trunk. The doors are automatically lockable and unlockable by means of a central locking system by way of a lock operation by means of key-operated locks in a pair of doors.
The central locking system is controlled by means of a first group of switching contacts on the locks and access to the interior of the motor vehicle is monitored by means of an anti-theft alarm system. The alarm readiness of the anti-theft alarm system is able to be activated by the switching contacts of the first group of switching contacts during the locking and is able to be deactivated during the unlocking. The alarm readiness of the anti-theft alarm system is displayed by an electro-optical display element in the locking buttons by means of flashing. The triggering of an alarm takes place by the alarm-ready anti-theft alarm system by at least one of its switching contacts of the group of second switching contacts changing from its inactive to the active state noting the accessing of the vehicle or its unauthorized use.
A motor vehicle with a closable and lockable trunk and at least two doors which can be automatically locked and unlocked by means of a central locking system by way of an operating of a lock by means of key-operated locks, is disclosed in the German Patent Document DE-88 10 641.1. The central locking system is controlled by means of a first group of switching contacts on the locks. An anti-theft alarm system monitors an accessing of the interior of the motor vehicle. An alarm readiness of the anti-theft alarm system is activated during the locking by means of the switching contacts of the first group of switching contacts and is deactivated during the unlocking. By means of two switching contacts, which record an accessing of the vehicle or its unauthorized use, the triggering of an alarm finally takes place by means of the alarm-ready anti-theft alarm system.
From the German Patent Document DE-3821561A, an arrangement has become known for the visual display of the readiness of a vehicle alarm system. For this purpose, an electro-optical display element is inserted into at least one locking button of a vehicle door lock. This display element generates a flashing signal when the anti-theft alarm system is switched to alarm-ready. The display element, which is constructed as a light-emitting diode, is operated in the pulse operation with a no-pulse period which is relatively long in comparison to the flash pulse.
Since the central locking system as well as the anti-theft alarm system are partly controlled by the same switching contacts, relatively high wiring expenditures are required. In the case of the above-mentioned system, it is also possible that, in the case of a malfunctioning or a partial malfunctioning of the central locking system, that the alarm system and its function display are nevertheless activated although possibly one or several doors or other openings of the motor vehicle are not properly locked.
There is therefore needed a motor vehicle having a central locking system and an anti-theft alarm system in which the wiring expenditures of both systems are reduced and an unintentional activating of the alarm system during a malfunctioning of the central locking system is avoided.
This need is met by a central locking and anti-theft alarm system which is controlled by a control unit common to both systems. The locked state and the unlocked state of all locks or doors and of the trunk lid is monitored by the control unit by means of a third group of switching contacts. When it is recognized that at least one signal, characterizing the locked state, of the switching contact or switching contacts of the third group of switching contacts, is absent after at least one key operation of a lock in the locking direction, the activating of the alarm system is prevented and a corresponding warning signal is emitted by way of the electro-optical display elements in the locking buttons.
The principal advantages of the invention are that, by the use of a common control unit for the central locking system and the anti-theft alarm system and the use of common switching contacts, the wiring expenditures are reduced. Further, the locked state and the unlocked state of all doors and of the trunk lid is monitored by the control unit by means of another group of switching contacts. When a signal of these switching contacts is recognized which does not occur after at least one operating of the key in a lock in the locking direction, an activating of the alarm system is prevented and a corresponding warning signal is emitted by way of the light emitting diodes in the door buttons.
In a further development of the invention, an activating of the alarm system is nevertheless possible in such a case. Likewise, after a manual locking of all doors, the alarm system can be activated by an operating of the key-operated lock in the locking direction.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.